Dna help in texas!

So I leave in texas. My husband was dumb enough to sign a birth certificate to a child that he doesn't even know is his. The little girl is 6 years old and the mom seems that all she wants is $. He's been wanting a dna and she won't budge. Now my question is if we take it to court. Will the court make her do the dna or will it be still up to her if she wants to comply? Any advise would help and TIA!